1. Field of the Invention
The present invention relates to a marine vessel running controlling apparatus which is applicable to a marine vessel having at least one pair of propulsion systems provided at a stern thereof, a marine vessel maneuvering supporting system and a marine vessel each including the marine vessel running controlling apparatus, and a marine vessel running controlling method.
2. Description of the Related Art
When a marine vessel travels toward or away from a wharf, a lateral maneuvering operation is performed to laterally move the hull of the marine vessel with the angular speed (stem turning speed) of the hull maintained constant (for example, at zero). In general, large-scale marine vessels include a plurality of small propulsion systems called “side thrusters” provided at a stem and other locations of a hull to laterally move the hull. The side thrusters each generate a propulsive force in a lateral direction of the hull. Thus, the hull can be laterally moved toward and away from the wharf by operating the side thrusters.
However, small-scale marine vessels, such as cruisers or boats, rarely include side thrusters because side thrusters cause various problems, such as an increase in costs, a need to modify the design of the hull to accommodate for installation of the side thrusters, and an increase in fuel consumption due to an increase in drag of the hull.
Cruisers and other leisure marine vessels are often operated by unskilled beginners. However, the lateral maneuvering of the small-scale marine vessels having no side thruster is very difficult, thereby requiring skills.
To this end, a marine vessel maneuvering apparatus which includes port-side and starboard-side propulsion systems provided at a stern of a marine vessel for facilitating the lateral maneuvering operation is disclosed, for example, in Japanese Patent No. 2810087. Japanese Patent No. 2810087 further discloses a mechanism for adjusting the orientation of the port-side and the starboard-side propulsion systems in accordance with each other, and a mechanism for operating engine throttles of the port-side and the starboard-side propulsion systems in accordance with each other. More specifically, the marine vessel maneuvering apparatus orients the port-side and starboard-side propulsion systems toward the center of the hull and generates a forward propulsive force from one of the propulsion systems and a reverse propulsive force from the other propulsion system.
However, the marine vessel maneuvering apparatus is not designed to calculate the directions and magnitudes of the propulsive forces required to be generated by the port-side and starboard-side propulsion systems for laterally moving the marine vessel in a desired direction. Therefore, the operator must manually operate the marine vessel for the lateral maneuvering operation to laterally move the marine vessel parallel, and thus must have a certain level of skill.
Further, the small-scale marine vessels are more likely to be influenced by disturbances than the large-scale marine vessels. More specifically, the instantaneous center (instantaneous rotation center) of the hull observed when the marine vessel is turned is easily changed by static disturbances such as the number and positions of passengers and the weight and positions of cargoes. Further, the instantaneous center is changed by dynamic disturbances such as winds and waves.
However, the prior art disclosed in Japanese Patent No. 2810087 is based on the assumption that the instantaneous center is fixed. Therefore, no consideration is given to the aforementioned disturbances. In reality, the lateral maneuvering operation for laterally moving the marine vessel toward and away from the wharf requires a substantial level of skill even with this prior art.